# Questions tagged [moment]

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### Calculating the moment/torque of a force applied over an area

This diagram shows a current carrying wire (from PQ) and a uniform magnetic field applied across the wire (from 85-90 cm) into the page, therefore the force is upward. How would one calculate the ...
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### Are there physics theorems that can prove maths theorems? Eg Pythagoras' Theorem

There's this recent post on maths overflow Which theorems have Pythagoras' Theorem as a special case? that has an answer by dxiv that appears to use a physics theorem to a prove a maths theorem, ...
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### Overturning torque on a car navigating a curve

The car shown above with mass M is turning to the left with an uniform angular speed W on a circular path with radius R. When the angular speed is increased to a critical value C, one of the normal ...
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### How is there moment for a group of forces which its resultant equals zero?

I am a beginner in mechanics, and when I was introduced to moments there was a theorem that says "if a set of forces acting on a rigid body has a resultant, then the algebraic sum of these forces ...
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### What does the dipole moment really represent?

Wikipedia gives the most general expression for the $n^{\rm th}$ moment $\mu_n$ of a physical quantity $\Lambda$ as: $$\mu_n = \int {\bf x}^n \space \lambda({\bf x}) \space \rm d^3 x$$ provided that ...
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### What exactly is moment? Why does it correspond to a rotation?

Wikipedia says: Moment is an expression involving the product of a distance and physical quantity. I don't quite get it. Moment is a vector, the cross product of the distance vector and the vector ...
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### Moments by normal stress

I am a bit confused with the following formula why is that the normal stress ($z$), not the normal stress ($x$), is involved in the formula for the moment around $x$, $Mx$? Likewise, My also equals ...
1 vote
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### What is mass moment? [duplicate]

My teacher gave the following definition while teaching chapter "Center of mass": "It is defined as the product of mass of the particle and distance of particle from point about which ...
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### Does "moment" have a single meaning in physics?

I am a high school student and I am curious about the word moment and what it means in different contexts, whether it has a definite meaning or not? I know it has some relation to different kinds of ...
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### What are the proper definitions of moment, couple, torque, 'moment of force'?

When I read some scientific articles I am getting confused with the interchange being used between Torque, Couple, Moment, 'Moment Of Force'. Have I got this correct? Moment is supposed to be some ...
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### Is the angular acceleration of a rigid body independent of the reference point?

I'm solving this particular question (refer to image) in which a rod is released from equilibrium after one of the two springs to which it is initially connected is disconnected. In order to calculate ...
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### Why does the Larmor precession frequency depend on $\vec{B}$ instead of $\vec{H}$?

From what I know: The magnetic field strength, $\vec{H}$, is the field generated by a free current flowing on an electric conductor. The magnetic flux density, $\vec{B}$, is a response of the medium ...
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### Intuition behind First moment of area and link to centroids

I essentially have the same question, however only concerning the First moment, as this user ,however none of the answers satisfy my questions. I understand that we are trying to get a sense of the ...
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### A problem about moment (torque ) [closed]

Everybody knows that moment of a force increases with distance. However, there is a problem about it that makes me confused these days: Let's take a look at this picture due to the formula M = F.d, ...
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### Physical meaning of internal bending moment

Here's the setup: The textbook, where this is from, first walks through how to find the strain and stress as a function of z, which is fairly straightforward. Then, it calculates the "total internal ...
1 vote
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### When calculating first moments of mass in cylindrical coordinates, can we use $r,\theta$ instead of $x,y$?

Usually when we want to find the center of mass of a 3D body, we need to find the first moments of mass about $x,y,z$, call them $M_x,M_y,M_z$. Defined by $$M_x = \iiint x\rho \ dV,$$ where $\rho$ ...
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### Finding distance of forces for maximum bending moment

I'm having a hard time looking for the distance ($x$) on which the forces must be located for a maximum bending moment. The reaction forces in $A$ and $B$ are dependant of the value of $x$, and so ...
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### Why does the load cause a moment around the support point in column buckling?

Here is a picture from Wikipedia, a free body diagram used to derive the maximum load in Euler's buckling theory. The moment is calculated around point A. It is claimed that the load $P$ causes a ...
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### Finding the moment at an angle [closed]

The question wants me to calculate the moment exerted on the nut, and the force (20 N) is applied at an angle (30 degrees) towards the pivot. I tried redrawing this as a triangle, with an angle of 30,...
1 vote
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### Simple model for friction in a pivot joint

Consider a pendulum that is attached to its pivot point using a hinge or ball bearing joint. What is a simple but reasonable approximation for modelling friction in that joint? Background: I'm ...
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### Can we construct a (specially designed) truss that is horizontal when supported from one end?

It is not possible to support a horizontal beam from one end, and the same is true for an I-Beam. I believe this can also be proven for a pipe, but that proof is just outside of my reach. But all of ...
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### How to take moment about point of contact in a hemisphere?

In question 3, i am able to solve first part but in second part i don't know how to take moments about point of contact or about center ?
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### What is a mass moment?

I am currently reading through a document Finding Moments of Inertia from MIT, page 4, and I am a little confused as to one of the concepts that they use. In this document, there is mention of a mass ...
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### Equilibrium of a body in torque problem

I was watching a video about torque in which the task was to find the force $F_2$ when a body is in equilibrium. The person in the video said that in order for the body to be in equilibrium, two ...
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### A bar weighs $2N$ and is $5m$ in length. What is the weight needed to balance the bar?

A bar weighs $2N$ and is $5m$ in length. What is the weight($M$) needed to balance the bar? I think I understand that the equation not including the weight of the bar would have 3*3=(5*1)+(2*M)\...
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### Moment on a body and on a simply supported beam

Consider a body on a frictionless floor being acted upon by a force F as shown in figure. Force acts on its centre of mass. (Centre of mass and centre of gravity coincide in this case, ie, both lie on ...
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### Difference between torque, moment and couple

I know the basics of them like Torque is force multiplied by the distance (from the point where there is no rotation like centre of gravity). Couple acts because of two equal and opposite forces ...
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### Teeter Totter Team Building Game

I recall doing a team building exercise where a team of about 4 people needed to balance a teeter totter, so that neither of the ends was touching the ground. They could achieve this by having the ...
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